Professor Nir Krakauer of City College co-authored an article in Earthzine entitled;
Vast swaths of the United States witnessed an unprecedented drop in windiness during the first half of 2015. This “wind drought” eclipses any previous event since 1979, in terms of both geographic extent and longevity, and affected states from Washington to Florida. Reanalysis data indicate that California, Oregon, Texas, and Washington reported their lowest recorded wind speeds in more than 30 years. Wind power generation plummeted as result, and since wind power now accounts for approximately 9.5 percent of electricity generation in the western United States (AWEA 2015), the impacts were far-reaching.
We provide an overview of the event within the context of California’s prolonged drought, and the record global warmth in 2015. The unparalleled low windiness is strongly linked to an abnormal high pressure ridge that was anchored over western North America from about June 2013 to April 2015 (Hartman 2015; Swain et al. 2014). This ridge was remarkable for its longevity and robustness, and appears to have drawn its prodigious strength from an unusual ocean warming event in the northeast Pacific (Seager et al. 2015; Wang et al. 2014, Hartmann 2015). The ocean warming was a record event (NCDC 2015; Marinaro et al. 2015), and helped to set the stage for the severe drought in California. El Niño was neutral (dormant) from May 2013 to about January 2015, and therefore unlikely to have played a role in this ocean warming event. Interestingly, the analyses of Wang et al. (2014) and Hartmann (2015) suggest that the northeast Pacific Ocean warming pattern is a precursor to El Niño, typically maximizing one year prior to the formation of the El Niño.
It remains an open question whether these extreme events can be linked to human activities or are within the envelope of natural variability. A companion paper further explores the record Northern Hemisphere warmth of 2015 (Cohan et al. 2016).